Following the unanimous approval by Lancaster County commissioners of a 304-megawatt solar plant outside Lincoln, one of the largest in the state, local opponents appealed. On those record-breaking days, keeping the lights on requires every power plant to show up and turn on. The summer peak could be a day when it’s cloudy and calm; the winter peak will definitely be a day when the sun sets early. If your gas plant had a tendency to break, it would be worth less. If you had a ton of wind, it would count more for the winter peak (when it’s windier) than for the summer.